Fetal growth retardation has been linked to elevated blood pressure in adult life. This association between birth weight and blood pressure is present in childhood and is amplified with age. However, the mechanisms that underlie this association are largely unknown. We examined the relationship between birth weight and forearm vascular resistance and forearm blood flow in children aged 9-12.7 years. A total of 58 children were randomly selected from a cohort of 1610 born at the University Hospital of the West Indies in Jamaica where adequate antenatal and delivery records were available. Blood pressure, heart rate and forearm blood flow (by venous occlusion plethysmography) were measured at rest and after cold pressor and mental arithmetic tests. There was a significant inverse correlation between birth weight and the change in the vascular resistance for the cold pressor test (r=-0.47; P<0.001) and the mental arithmetic stress test (r=-0.26; P=0.05). The log ratio of vascular resistance under stress to resting decreased by 0.289 units per kg of birth weight (95% CI: 0.145-0.434; P=0.0002). Lower birth weight is associated with increased vascular responsiveness. Increased vascular resistance might be one mechanism linking fetal growth to subsequent elevated blood pressure.....read more